feat: add example for effective go krm function

go/Makefile

@@ -23,7 +23,7 @@ fmt: $(MODULES)
 lint: $(MODULES)
 	@for f in $(^D); do \
 	(cd $$f; echo "Checking golangci-lint $$f"; \
-	(which $(GOPATH)/bin/golangci-lint || go install github.com/golangci/golangci-lint/cmd/golangci-lint@v1.44.2); \
+	(which $(GOPATH)/bin/golangci-lint || go install github.com/golangci/golangci-lint/cmd/golangci-lint@v1.50.1); \
 	$(GOPATH)/bin/golangci-lint run ./...); \
 	done
 

go/get-started/go.mod

@@ -0,0 +1,38 @@
+module github.com/GoogleContainerTools/kpt-functions-sdk/go/get-started
+
+go 1.19
+
+require (
+	github.com/GoogleContainerTools/kpt-functions-sdk/go/api v0.0.0-20221018174030-e63010a12b00 // indirect
+	github.com/GoogleContainerTools/kpt-functions-sdk/go/fn v0.0.0-20221018174030-e63010a12b00 // indirect
+	github.com/PuerkitoBio/purell v1.2.0 // indirect
+	github.com/PuerkitoBio/urlesc v0.0.0-20170810143723-de5bf2ad4578 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/go-errors/errors v1.4.2 // indirect
+	github.com/go-logr/logr v1.2.3 // indirect
+	github.com/go-openapi/jsonpointer v0.19.5 // indirect
+	github.com/go-openapi/jsonreference v0.20.0 // indirect
+	github.com/go-openapi/swag v0.22.3 // indirect
+	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/google/gnostic v0.6.9 // indirect
+	github.com/google/go-cmp v0.5.9 // indirect
+	github.com/google/gofuzz v1.2.0 // indirect
+	github.com/josharian/intern v1.0.0 // indirect
+	github.com/mailru/easyjson v0.7.7 // indirect
+	github.com/monochromegane/go-gitignore v0.0.0-20200626010858-205db1a8cc00 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/stretchr/testify v1.8.1 // indirect
+	github.com/xlab/treeprint v1.1.0 // indirect
+	golang.org/x/net v0.1.0 // indirect
+	golang.org/x/sys v0.1.0 // indirect
+	golang.org/x/text v0.4.0 // indirect
+	google.golang.org/protobuf v1.28.1 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+	k8s.io/apimachinery v0.25.3 // indirect
+	k8s.io/klog/v2 v2.80.1 // indirect
+	k8s.io/kube-openapi v0.0.0-20221012153701-172d655c2280 // indirect
+	sigs.k8s.io/kustomize/kyaml v0.13.9 // indirect
+)

go/get-started/golden_test.go

@@ -0,0 +1,31 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package main
+
+import (
+	"context"
+	"testing"
+
+	"github.com/GoogleContainerTools/kpt-functions-sdk/go/fn"
+	"github.com/GoogleContainerTools/kpt-functions-sdk/go/fn/testhelpers"
+)
+
+const TestDataPath = "testdata"
+
+func TestFunction(t *testing.T) {
+	fnRunner := fn.WithContext(context.TODO(), &YourFunction{})
+	// This golden test expects each sub-directory of `testdata` can has its input resources (in `resources.yaml`)
+	// be modified to the output resources (in `_expected.yaml`).
+	testhelpers.RunGoldenTests(t, TestDataPath, fnRunner)
+}

go/get-started/main.go

@@ -15,24 +15,33 @@
 package main
 
 import (
-	"fmt"
+	"context"
 	"os"
 
 	"github.com/GoogleContainerTools/kpt-functions-sdk/go/fn"
 )
 
-// EDIT THIS FUNCTION!
-// This is the main logic. rl is the input `ResourceList` which has the `FunctionConfig` and `Items` fields.
-// You can modify the `Items` and add result information to `rl.Result`.
-func Run(rl *fn.ResourceList) (bool, error) {
-    // Your code
+var _ fn.Runner = &YourFunction{}
+
+// TODO: Change to your functionConfig "Kind" name.
+type YourFunction struct {
+	FnConfigBool bool
+	FnConfigInt  int
+	FnConfigFoo  string
+}
+
+// Run is the main function logic.
+// `items` is parsed from the STDIN "ResourceList.Items".
+// `functionConfig` is from the STDIN "ResourceList.FunctionConfig". The value has been assigned to the r attributes
+// `results` is the "ResourceList.Results" that you can write result info to.
+func (r *YourFunction) Run(ctx *fn.Context, functionConfig *fn.KubeObject, items fn.KubeObjects, results *fn.Results) bool {
+	// TODO: Write your code.
+	return true
 }
 
 func main() {
-	// CUSTOMIZE IF NEEDED
-	// `AsMain` accepts a `ResourceListProcessor` interface.
-	// You can explore other `ResourceListProcessor` structs in the SDK or define your own.
-	if err := fn.AsMain(fn.ResourceListProcessorFunc(Run)); err != nil {
+	runner := fn.WithContext(context.Background(), &YourFunction{})
+	if err := fn.AsMain(runner); err != nil {
 		os.Exit(1)
 	}
 }

go/get-started/testdata/test1/_expected.yaml

@@ -0,0 +1,41 @@
+apiVersion: config.kubernetes.io/v1
+kind: ResourceList
+items:
+- apiVersion: apps/v1
+  kind: Deployment
+  metadata:
+    name: nginx-deployment
+    labels:
+      app: nginx
+  spec:
+    replicas: 3
+    selector:
+      matchLabels:
+        app: nginx
+    template:
+      metadata:
+        labels:
+          app: nginx
+      spec:
+        containers:
+        - name: nginx
+          image: nginx:1.14.2
+          ports:
+          - containerPort: 80
+- apiVersion: v1
+  kind: Service
+  metadata:
+    name: test
+  spec:
+    selector:
+      app: MyApp
+    ports:
+    - protocol: TCP
+      port: 80
+      targetPort: 9376
+functionConfig:
+  apiVersion: fn.kpt.dev/v1alpha1
+  kind: YourFunction
+  metadata:
+    name: test
+  fnConfigFoo: example

go/get-started/Dockerfile → go/get-started/testdata/test1/_fnconfig.yaml

@@ -12,13 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM golang:1.17-alpine3.15
-ENV CGO_ENABLED=0
-WORKDIR /go/src/
-COPY go.mod go.sum ./
-RUN go mod download
-COPY . .
-RUN go build -o /usr/local/bin/function ./
-FROM alpine:3.15
-COPY --from=0 /usr/local/bin/function /usr/local/bin/function
-ENTRYPOINT ["function"]
+apiVersion: fn.kpt.dev/v1alpha1
+kind: YourFunction
+metadata:
+  name: test
+fnConfigFoo: example

go/get-started/data/resources.yaml → go/get-started/testdata/test1/resources.yaml

@@ -15,7 +15,7 @@
 apiVersion: v1
 kind: Service
 metadata:
-  name: my-service
+  name: test
 spec:
   selector:
     app: MyApp

go/hack/update-license.sh

@@ -17,4 +17,10 @@
 # don't add licenses to the site directory, it will break the docs
 # and will add them to the theme which is a submodule (bad)
 command -v addlicense || go install github.com/google/[email protected]
-find . -print0 | xargs "$GOBIN"/addlicense -y 2022 -l apache
+# - `addlicense` skips the .yaml files (specifically for golden test _expected.yaml) to avoid the conflict where
+# the `addlicense` adds unexpected license header that fails the golden tests diff-comparison in _expected.yaml.
+# - the [0-9a-z] is a trick to avoid using `**/**/*.yaml` directly which hits the shellcheck SC2035. SC2035 only accepts
+# ./*glob* or -- *glob* which can't be recoganized by addlicese.
+# See https://www.shellcheck.net/wiki/SC2035
+find . -print0 | xargs "$GOBIN"/addlicense -y 2022 -l apache -ignore [0-9a-z]**/**/_expected.yaml
+